1. Field of the Invention
The present invention relates to a vibratory drive apparatus, such as a vibration wave actuator, and specifically relates to a vibratory drive apparatus that is favorable for use in, e.g., a mechanism that corrects blurring due to hand movements in an optical apparatus such as a camera or binoculars, or a drive mechanism for a table.
2. Description of the Related Art
Conventionally, vibration wave actuators, which are vibratory drive apparatuses that move a driven element in contact with a plurality of vibrators in a plurality of different directions (desired directions), are known. Among such vibration wave actuators, a pressure application-type vibration wave actuator in which a magnet is employed for a driven element is known (Japanese Patent Application Laid-Open No. 2009-027769). Also, Japanese Patent Application Laid-Open No. 2007-312519 proposes a vibratory drive apparatus in which a magnetic member is arranged in a space between a vibrator and a driven element. More specifically, the vibratory drive apparatus is configured so that projection portions that project from a first surface of a vibrator and are in contact with the driven element are formed, and a magnet is arranged between the first surface of the vibrator and the driven element to attract the driven element by means of a magnetic force. FIGS. 14A and 14B illustrate the configuration of a linear vibration wave actuator described in the Japanese Patent Application Laid-Open No. 2007-312519. In FIGS. 14A and 14B, a vibrator 52 is supported by a holding member 57 via an elastic supporting member 56 while preventing the hindering of vibration of the vibrator 52 by the elastic supporting member 56. Furthermore, a magnetic member 65 including a magnet is arranged on the holding member 57 and between projection portions 58 formed on an upper surface of the vibrator 52. The magnetic member 65 is held in a state in which the magnetic member 65 is not in contact with the vibrator 52 and a driven element 70, and generates a magnetic attraction force MF that attracts the vibrator 52 and the driven element 70 in a Z-direction. Pressure is applied by means of the magnetic attraction force.
Also, as another example of vibratory drive apparatuses driving a driven element by means of a vibrator, such as ultrasonic motors, there are ones using a vibrator obtained by integrating a vibration plate including, for example, an elastic metal member, and a piezoelectric element (electro-mechanical energy conversion element) by means of, e.g., adhesion. Among such vibrator-used vibratory drive apparatuses as described above, ones using magnetic force to generate pressure applied to a vibrator and a driven element have been proposed. U.S. Pat. No. 7,425,770 proposes a vibratory drive apparatus including a permanent magnet in at least a part of a vibrator. Also, U.S. Pat. No. 7,518,286 discloses a vibratory drive apparatus including a permanent magnet in at least a part of a driven element.